To add an id attribute to element:
- Use the setAttribute(name, value)
- The first param will specify the name of the attribute
- The second param is a string continaing the value to assign to the attribute
- Use document.querySelector() to select the element
For example:
CSS
#bg{background:blue}
HTML
<p class="note">give me background color</p>
JavaScript
const note = document.querySelector(".note");
note.setAttribute("id", "bg");
So, in the above example the background color is set using the id "bg".
Notice "bg" is set using the setAttribute() function.
Obviously you might need a more dynamic senario to use a technique like this.
Like when a button is clicked add the id attribute or somehting to that effect.